The Iowa State Fair annually draws turkey callers, cow-chip throwers and piemakers from across the Hawkeye State. This year's fair, which begins next week, is attracting a crowd of competitors from farther afield: possible White House contenders hunting for votes ahead--way ahead--of the Iowa presidential caucuses in January 2008. Democratic Senators Evan Bayh of Indiana and Joe Biden of Delaware and the Republican former House Speaker Newt Gingrich are all expected to swoop in to smile, shake hands and maybe taste the fair's famed fried Twinkies. Also planning to visit Iowa in August: 2004 Democratic running mates John Kerry of...